Wetland biodiversity in Aotearoa New Zealand: an eDNA perspective on exotic and non-exotic species

Invasive species threaten biodiversity in Aotearoa New Zealand. In wetlands − significant sites that provide an array of ecosystem and cultural services but represent <10% of their original extent − invasive species can affect hydrological function, nutrient regimes and overall ecological functionality. Environmental DNA (eDNA) has emerged as a valuable biomonitoring technique for cataloguing biodiversity and detecting biological incursions, but little is known about how biodiversity varies in wetlands over fine and broad spatial scales. Here, we examined the publicly available eDNA database of Wilderlab New Zealand, retrieving data from 26 sites across the country to characterise taxonomic diversity patterns, including the extent of exotic and non-exotic (native and endemic) species. We found significant spatial variation in biodiversity – even among neighbouring sites – and a pattern whereby all sites had ≥50% exotic species in their total species tally. Our results provide new information on the current state of wetland biodiversity in Aotearoa New Zealand and highlight the value of eDNA databases for generating new insights from publicly shared data. They also emphasise an urgent need for greater resource allocation to conservation and restoration initiatives in Aotearoa New Zealand that will ensure the persistence of treasured native and endemic wetland species.

入侵物种威胁新西兰奥特亚罗瓦（Aotearoa New Zealand）的生物多样性。湿地作为兼具多样生态系统服务与文化服务的重要生境，其原始面积目前仅占10%以下。入侵物种会对湿地的水文功能、营养盐循环及整体生态功能造成负面影响。环境DNA（Environmental DNA, eDNA）已成为生物编目与检测生物入侵的高效生物监测技术，但目前学界对湿地生物多样性在精细与大空间尺度下的变化规律仍知之甚少。本研究调取了新西兰Wilderlab New Zealand公开的eDNA数据库，从全国26个采样点位获取数据，以解析湿地的分类多样性格局，包括外来物种与非外来物种（本土物种及特有物种）的占比情况。研究结果显示，即便在相邻采样点位间，湿地生物多样性也存在显著的空间异质性；且所有采样点位的物种总数中，外来物种占比均不低于50%。本研究结果为新西兰奥特亚罗瓦湿地生物多样性的现状提供了新的认知，并凸显了eDNA数据库通过公开共享数据挖掘以获取新研究见解的重要价值。同时，本研究也强调，新西兰奥特亚罗瓦亟需加大对湿地保护与修复项目的资源投入，以保障本土及特有湿地珍稀物种的存续。